1. Field of Invention
This invention relates to a self-lubricating coupling and, more particularly, to a self-lubricating coupling for use with rotating equipment such as rolling mills where lubrication is critical but access for manual lubrication is extremely limited.
The use of gear-type spindle couplings is old in the art. The gear-type couplings have been used because of their ability to accommodate the misalignment requirements of rolling mill service coupled with a far longer life than that possible with other coupling forms. However, to use the gear-type coupling to maximum efficiency, it is necessary that the coupling be properly lubricated. If proper lubrication is not maintained, coupling failure usually results with the loss of operating time and the expense of repairing or replacing the coupling.
2. Description of the Prior Art
In some cases, lubrication of the gear-type coupling has heretofore been accomplished manually. While in most instances, manual labor can satisfactorily lubricate the coupling, it has very serious drawbacks. The cost of manual labor to accomplish the task is high. Not only are several laborers required, but at least one of them must possess the requisite skill to supervise the operation to assure it is properly performed. The manual lubrication also causes excessive downtime for the mill which in itself can be extremely costly during periods of peak operation. Also, the lubrication is carried out in limited spaces, under extremely difficult working conditions. Noise and temperatures are necessarily high and the safety of the workmen in the cramped work spaces can be compromised.
The present invention overcomes the foregoing problems of the prior art, by permitting the automatic lubrication of gear-type spindle couplings at the roll and pinion ends, and limiting the need for manual lubrication of the gear teeth.
The invention provides a gear-type spindle coupling adapted to operably engage the roll and pinion end sleeve with internal gear teeth. The spindle shaft of the coupling has a plurality of internal reservoirs, adapted to receive a supply of lubricant through external fittings. The reservoirs are formed so that their rear walls are biased to exert a pressure on the lubricant to urge it toward the roll and pinion ends of the spindle.
The spindle shaft has spring assemblies designed to engage the thrust button on each end to maximize the alignment of the roll end with the spindle of the coupling. The spring assemblies include springs mounted on a shaft between the plunger and slidably mounted cartridge shoulder. When the roll shaft is inserted into the roll sleeve the springs are compressed and move toward the cartridge shoulder in the spring cartridge channel.
A piston is fixably attached to the spring guide rod to move in cooperation with the rod, forward toward the roll end and toward the pinion end of the coupling when the roll shaft is not in operable contact with the spindle and rearward when the roll shaft is in cooperation with the spindle. The back face of the piston together with the spring guide rod and cartridge form the forward wall of the lubricant reservoir.
When the spring assembly is compressed by the roll and pinion ends, a plenum is formed in the spring cartridge channel by the movement of the piston. When the piston is withdrawn from the plenum, the pressure in the plenum is less than that exerted on the lubricant. The pressure differential opens a one-way valve and causes the lubricant to flow into the plenum. Release of the compressive force on the springs causes second spring loaded one-way valves on the roll and pinion end walls of the plenum to open. When the one-way valve opens, lubricant flows from the plenum through the spring assembly between the spindle shaft and the roll and pinion thrust buttons and into the vicinity of the teeth of the sleeves and hubs. Thus, a supply of lubricant is available to lubricate the gear teeth, whenever the roll shaft is removed, during the roll changing operation.